Rapidly growing interest in using nanoparticles (NPs) for biomedical applications has increased concerns about their safety and toxicity. In comparison with bulk materials, NPs are more chemically active and toxic due to the greater surface area and small size. Understanding the NPs’ mechanism of toxicity, together with the factors influencing their behavior in biological environments, can help researchers to design NPs with reduced side effects and improved performance. After overviewing the classification and properties of NPs, this review article discusses their biomedical applications in molecular imaging and cell therapy, gene transfer, tissue engineering, targeted drug delivery, Anti-SARS-CoV-2 vaccines, cancer treatment, wound healing, and anti-bacterial applications. There are different mechanisms of toxicity of NPs, and their toxicity and behaviors depend on various factors, which are elaborated on in this article. More specifically, the mechanism of toxicity and their interactions with living components are discussed by considering the impact of different physiochemical parameters such as size, shape, structure, agglomeration state, surface charge, wettability, dose, and substance type. The toxicity of polymeric, silica-based, carbon-based, and metallic-based NPs (including plasmonic alloy NPs) have been considered separately.
Biofilm formation can lead to problems in healthcare, water distribution systems, food processing and packaging, industrial manufacturing, marine industries, and sanitation. These microbial communities can proliferate on biotic or abiotic surfaces, and are responsible for human disease and decreasing production efficiency and service equipment life in many industrial fields. The formation of biofilm starts with the attachment of bacteria to the surface, followed by bacterial proliferation and maturation of the microbial community. After forming a biofilm, bacteria not resistant to antimicrobial agents in their planktonic forms can turn resistant. The antibiotic resistance of bacterial biofilm, and the association of biofilms in generating infectious diseases in humans, highlight the need for designing novel and successful antibacterial, anti-biofilm, or anti-infection materials. This paper aims to review the mechanism of biofilm formation, the impact on different industries, the interaction mechanism of nanoparticles with bacteria, and strategies to design anti-biofilm materials. Examples of designing anti-infection bio-implants, coatings, medical devices, wound dressings, and sutures are reviewed.
Critical-sized bone defects, or CSDs, are defined as bone defects that cannot be regenerated by themselves and require surgical intervention via employing specific biomaterials and a certain regenerative strategy. Although a variety of approaches can be used to treat CSDs, poor angiogenesis and vascularization remain an obstacle in these methods. The complex biological healing of bone defects depends directly on the function of blood flow to provide sufficient oxygen and nutrients and the removal of waste products from the defect site. The absence of vascularization can lead to non-union and delayed-union defect development. To overcome this challenge, angiogenic agents can be delivered to the site of injury to stimulate vessel formation. This review begins by introducing the treatment methods for CSDs. The importance of vascularization in CSDs is subsequently highlighted. Delivering angiogenesis agents, including relevant growth factors, cells, drugs, particles, cell secretion substances, their combination, and co-delivery to CSDs are fully explored. Moreover, the effects of such agents on new bone formation, followed by vessel formation in defect areas, are evaluated.
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